Abstract

A comparison between the conventional photothermal frequency scan method and the recently developed photothermal lock‐in rate window technique for thermal diffusivitymeasurements of materials, is presented. In this comparison, a completely noncontact experimental configuration has been utilized based on infrared photothermalradiometry. This work shows that for thick materials with long thermal transport times across the sample where low‐frequency measurements are required, the frequency scan method may be more appropriate due to its simplicity. The rate window method, however, gives superior signal‐to‐noise ratio (SNR) for materials with very short thermal transport times such as metal foils, which otherwise require high frequency, low SNR measurements. A further advantage of the pulse duration‐scanned rate‐window mode is that it does not require knowledge of the instrumental transfer function as an input.